Cutting gas nozzles are known, for example, from JPH 10 216978A or from DE 198 53 735 C1. Cutting gas nozzles can be employed on a laser machine tool such as is disclosed in DE 10 2013 210 844 B3, for example.
Different cutting gas nozzles that have different external or internal contours, different shaped nozzle openings, and different nozzle diameters are required for cutting different materials (e.g., construction steel, stainless steel, aluminum, etc.) in different material thicknesses with the aid of a laser beam. To accommodate this diversity while reducing the frequency of necessary nozzle changes, a cutting gas nozzle for a laser machining head that directs a cutting gas through an inner nozzle onto the processing location and directs an auxiliary gas through an annular gap nozzle that surrounds the inner nozzle onto the processing location is known from JPH 10 216978A. The annular gap nozzle with the aid of a screw thread can be axially advanced and reversed relative to the inner nozzle to change the nozzle opening (the nozzle cross-sectional area) of the annular gap nozzle and to thus influence the gas flow of the auxiliary gas.
A laser machining head in which a cutting gas nozzle having an inner nozzle and having an annular gap nozzle is disposed in a hollow piston that is guided in a displaceable manner is known from DE 198 53 735 C1. In the operation of the laser machining head, a gas cushion is formed between the workpiece surface and the end face of the hollow piston. The gap dimension between the workpiece surface and the end face of the hollow piston can be adjusted with the aid of the gas pressure, wherein the inner nozzle and the annular gap nozzle can be pressurized with different pressures.